Discrimination of internal fault from magnetising inrush current in power transformers based on sine-wave least-squares curve fitting method

This study deals with a method for discrimination between magnetising inrush and internal fault currents in three-phase transformers based on sine-wave curve fitting. A sine wave is fitted to the normalised differential current by using the least-squares technique for each phase. The difference between the normalised differential currents and the fitted signals are calculated, which are hereafter named residual signals (RSs). Maximum range of the RSs variations is utilised for the definition of a simple criterion. Based on this criterion, the discrimination is realised within less than a half cycle of power frequency. In order to eliminate the impact of the current transformer (CT) saturation on the performance of the proposed technique, the currents are compensated by a CT saturation compensation algorithm in the first step. The proposed method is evaluated and compared with some well-known methods by a large number of simulation and experimental data. Furthermore, the proposed algorithm is evaluated in the case of a transformer, which is fed through a feeder with series capacitors. The results confirm that reliability, accuracy and speed response of the proposed technique is more than the other methods.

[1]  Erdal Kiliç,et al.  Modeling and real-time fault identification in transformers , 2008, J. Frankl. Inst..

[2]  Xiaotan Zhao,et al.  Identification of magnetizing inrush currents of power transformers based on features of flux locus , 2003, Sixth International Conference on Electrical Machines and Systems, 2003. ICEMS 2003..

[3]  Ge Baoming,et al.  An equivalent instantaneous inductance-based technique for discrimination between inrush current and internal faults in power transformers , 2005 .

[4]  Kuniaki Yabe,et al.  Power differential method for discrimination between fault and magnetizing inrush current in transformers , 1996 .

[5]  Xu Yan,et al.  A New Technique to Identify Internal Faults and Inrush Currents Using Morphological Gradient with Adaptive Filtering , 2006, 2006 International Conference on Power System Technology.

[6]  Yunhua Li,et al.  Using combined characteristics to identify inrush current and internal fault current of traction transformer , 2011, 2011 6th IEEE Conference on Industrial Electronics and Applications.

[7]  A. G. Phadke,et al.  A New Computer-Based Flux-Restrained Current-Differential Relay for Power Transformer Protection , 1983, IEEE Power Engineering Review.

[8]  M. Khanabadi,et al.  A novel technique to identify inrush current based on adaptive neuro fuzzy , 2011, 2011 10th International Conference on Environment and Electrical Engineering.

[9]  Saeed Jazebi,et al.  Magnetizing inrush current identification using wavelet based gaussian mixture models , 2009, Simul. Model. Pract. Theory.

[10]  M. E. Hamedani Golshan,et al.  A new method for recognizing internal faults from inrush current conditions in digital differential protection of power transformers , 2004 .

[11]  Subhransu Ranjan Samantaray,et al.  Decision Tree based discrimination between inrush currents and internal faults in power transformer , 2011 .

[12]  Jing Ma,et al.  A novel method for discrimination of internal faults and inrush currents by using waveform singularity factor , 2010, 2010 Conference Proceedings IPEC.

[13]  Z.Q. Bo,et al.  A new method to identify inrush current based on error estimation , 2006, IEEE Transactions on Power Delivery.

[14]  Y C Kang,et al.  TRANSFORMER PROTECTION RELAY BASE ON INDUCED VOLTAGES , 2003 .

[15]  Pei Liu,et al.  Improved operation of differential protection of power transformers for internal faults based on negative sequence power , 1998, Proceedings of EMPD '98. 1998 International Conference on Energy Management and Power Delivery (Cat. No.98EX137).

[16]  M. Suzuki,et al.  Digital protection method for power transformers based on an equivalent circuit composed of inverse inductance , 1988 .

[17]  Okan Ozgonenel,et al.  A New Method for Fault Detection and Identification of Incipient Faults in Power Transformers , 2008 .

[18]  J. Faiz,et al.  A novel wavelet-based algorithm for discrimination of internal faults from magnetizing inrush currents in power transformers , 2006, IEEE Transactions on Power Delivery.

[19]  Syed Nasar,et al.  Electric Power Systems , 1972 .

[20]  M.F. El-Naggar,et al.  A novel image-based approach for discrimination between internal faults and magnetizing inrush currents in power transformers , 2007, 2007 Australasian Universities Power Engineering Conference.

[21]  Jinyu Wen,et al.  Discrimination between fault and magnetizing inrush current in transformers using short-time correlation transform , 2002 .